A man has been arrested at Heathrow Airport on suspicion of possessing information which could be useful to a person committing or preparing an act of terrorism.
Police said the 29-year-old man was stopped as he was about to board a flight to Saudi Arabia on Monday morning.
He was initially detained under the Terrorism Act and subsequently arrested.
A home in west London is being searched by officers from Scotland Yard's Counter-Terrorism Command and several electronic devices have been seized for analysis.
The man has been taken to a London police station where he is being questioned.
Several terror arrests have been made in the UK since the start of the year, including a 21-year-old man arrested on suspicion of attempting to join Isis in Syria in April.
